Method of production of a branched organosilicone polymerous polynuclear adsorbent of high molecular toxins and this adsorbent

ABSTRACT

The synthesis of an organosilicone adsorbent, which can be used in medicine as an enterosorbent for the removal of organic and toxic metabolites from the body obtains a new branched organosilicone polymerous polynuclear adsorbent of high molecular toxins. According to the analysis by Si 29 NMR method, the adsorbent contains superpositions of at least three silicon signals with values of chemical shifts −80 ppm, −100 ppm, −115 ppm, and ratio of their integral intensities close to 2:2:1. This adsorbent has a high adsorption activity, and the synthesis of its obtaining can reduce labour costs, increase output of the target product in manufacture and reduce their self-cost/net-cost.

CROSS-REFERENCE TO RELATED APPLICATIONS

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BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to the synthesis of an organo silicone adsorbent,which can be used in various sectors of the national economy, especiallyin medicine as an enterosorbent for the removal of organic and toxicmetabolites from the body, including in various types of pathology ofthe gastrointestinal tract for the internal, as well as for the externaluse.

2. Description of Related Art Including Information Disclosed Under 37CFR 1.97 and 37 CFR 1.98.

The interest in the use of sorbents for medical purposes has increaseddramatically since the 80s of the last century. This was preceded bystudies of Greek scientists who demonstrated the possibility ofeffective removing toxic products from the body, formed in it as aresult of diseases, by cleaning the blood with the help of activatedcharcoal. The obtained results gave a powerful push to the developmentof new methods of treatment and the development of new types ofsorbents.

In general, sorbents are classified according to the form, chemicalnature of the material, texture, type of interaction with the sorbate.The texture is associated with the composing of the primary particles(globules) of the material and thus the formation of pores of a certainsize. Each sorbent is characterized by the pore size, pore volume,specific surface, where adsorption occurs—concentration of the substanceof the adsorbate (toxin) in the porous space and on the outer geometricsurface of the sorbent.

The sorption capacity of porous materials is known to be largelydetermined by the size of the surface, available for adsorbatemolecules, and depends on the exclusive effect. With the growth of thespecific surface and, correspondingly, with the decrease in the averagepore size of the sorbent, the exclusive effect intensifies, which leadsto the appearance of a maximum on the curve of adsorption dependence(per unit of weight of the sorbent) on the pore size.

The classical method for determining these parameters is based on themeasurement of the specific surface (S), for example, on nitrogenadsorption, the specific pore volume V—by benzol capillary condensation,the average pore diameter (D) is calculated by formula D=4V/S.

Activated charcoal is of widespread as a sorbent. (Vidal Formulary.Medicinal Products of Russia.—M.: OVPEE—AstraPharm Service, 2000—P.3-8). It is convenient to use, since it is manufactured in the form oftablets, powder and is used in the chemical, food, pharmaceutical andmedical industries.

However activated charcoal has significant disadvantages: moderateadsorption activity and low selectivity of sorption action, such as inrelation to cholesterol, bilirubin, urea, and uric acid, which areusually removed from the body by organs of the endocrine system.

When applying it, constipation, vomiting, inhalation of coal dust in thelungs are possible; during chronic use—hypovitaminosis, impaired suctionfrom the gastrointestinal tract of nutrients are possible.

Activated charcoal is contraindicated in case of ulcerous lesions of thegastrointestinal tract, stomach bleeding and for children.

There is also another enterosorbent, the product of non-linearcondensation of methylsilicic acid (in the chemicalmeaning—polymethylsiloxane polyhydrate), known under the trade nameEnterosgel (TM).

International Patent Application WO/2011/075095 discloses the method ofpreparation of hydrogel methylsilicic acid from methyltriethoxysilane(MTES) and aqueous ethanol solution with a volume fraction of ethylalcohol from 60 to 96.5%, which is treated with a mixture ofhydrochloric acid and purified water.

The hydrolysis of MTES is carried out in the presence of an acidcatalyst, followed by alkaline treatment at temperature of 16-30° C.,with the stand of the reaction mass (for maturation for at least 7.5 h),by grinding the obtained alcogel methylsilicic acid, followed by washingit with treated water at a rate of 2-4 1 per hour before receivinghydrogel.

However, this method of synthesis also has some disadvantages.Sufficient volumes of alcohol are required for the hydrolysis, a longprocess of “maturation” of gel, high water flow during washing, and thepossibility of finding alcohol in pores of the finished product limitthe medical use of the sorbent.

From Patent RU 2111979, a method for the synthesis of polymericcompounds of methylsilicic acid is known with the following chemicalformula

{(CH₃SiO_(1.5))nH₂O}., where n=44-49,

as an adsorbent of median-molecular metabolites.

Medium-molecular metabolites are substances with a molecular weight ofabout 500-5000 Da. As a rule, these products are products ofdisintegration/decay of proteins, which plays an important role in thephenomena of intoxication.

However, macromolecular compounds—bacterial toxins, viruses make notless, but more often and more important component of intoxication.

As it is known from the aforementioned patent, hydrogel of methylsilicicacid (HGMSA) is synthesized by polycondensation of solution of sodiummethylesiliconate (or potassium) in concentration from 1.75 to 2.30mol/1 by adding solution of strong acid (for example, HCl or H2SO4) attemperature of the reaction mixture from +10 to +35° C. until theformation of hydrogel, which, after standing for 30-90 minutes (the“maturation” process), is pulverized and then activated by the action ofa dilute solution of strong acid at concentration from 0.04 to 0.15g·equ/1 followed by washing with water to neutralize the reaction.

The disadvantage of this well-known method of obtaining HGMSA is that itdoes not take into account different amount of methylsiliconate sodium(potassium) and strong acid, necessary for the reaction, which makesthis method poorly! ! reproducible, and the product is hardly suitablefor adsorption of high molecular toxicants, which is of great importancein the medical use.

Patent RU 2293744 describes the process of synthesizing a compound whichis referred to as 1,1,3,3-tetrahydroxy-1,3-dimethyldisiloxanepolyhydrate, and which corresponds to the formula:

where n from 88 to 98

The essence of the method of obtaining this polyhydrate is theinteraction of the original chemical raw materials—“ . . . alkalinesolution of dioxymethylsilicic acid sodium formula CH₃Si(OH)₂ONa withdensity 1.16-1.19 g/cm3 (20 fractions) with sulfuric acid (specificweight 1.195-1.205 g/cm3) (6 fractions), cooled to temperature of 0-5°C., stirring for 90 minutes”.

Meanwhile, neither from the description of this patent nor from anotherwell-known source of the state of art know this reagent! or show the wayof obtaining it/the one.

All known publications, related or connected with the subject/topic ofsilicone hydrogels, are directly or indirectly referred to works of thefounder of the school of silicon organic polymers, Academician K.Andrianov and other authors.

In all known sources of information, it is stated that predictablesilicones of mono-organosilicones have a complex structure, dependent onthe method of preparation, and are polymeric compounds, but not at allmonomers with the formula CH₃Si(OH)₂ONA.

Upon completion of the reaction and maturation of the target product,the resulting mixture is washed with water in order to remove unreacteddioxymethyl silicon sodium from pores, which is neutralized by washingat room temperature with solution of sulfuric acid with a specificweight of 1.001 to pH of rinsing water, equal to 4.0, and then withpurified water to pH of washing water 5.0-7.0, and pulverized.

The essence of the invention under Patent RU 2293744 is confirmed byExamples 1-3 and the data of the elemental composition, given in thedescription.

However, according to publication of K. Andrianov, Element OrganicChemistry Methods. Silicon. M.: Nauka, 1968, pp. 550-551, 602-603, thereis the method of preparation of methyl siliconate sodium by hydrolyzingmethyl trichlorosilane by excess of aqueous alkaline solution. It isassumed that in this case polymers of the following kind are formed:

“Similar phenomena occur during the hydrolysis of methyl trichlorosilaneby aqueous alkaline solution, taken with excess (for example, 4 mol per1 mol of methyl trichlorosilane). In this reaction, block is sodiumions, which form in polymer silanolate groups, which interfere with thereaction between chains:

The authors of the claimed invention consider that the compound,protected by Patent RU 2293744 cannot be obtained in principle.

As shown by the authors' own experiments, it is impossible to obtain, insuch a well-known way, the target product—gel, since stirring within 90minutes does not allow it to be formed—to “precipitate out”, that is toturn into the gel state, but on the contrary, there is a paste/pastyamorphous mass, the output of which after pulverising and decantingcannot be 96%.

In connection with the above, there is a task of obtaining newadsorbents on the basis of organosilicones, which would allow toincrease their adsorption activity, reduce labour costs, increase theoutput of the target product in manufacturing/while producing, reducetheir self-cost/net-cost.

BRIEF SUMMARY OF THE INVENTION

Assigned task is solved by creating a method for obtaining of a newbranched organosilicone polymer polynuclear silicon compound(polymethylsilsesquioxane), which according to the analysis by Si²⁹NMRmethod, contains at least three types of silicon atoms, characterized bythe presence of a superposition of three silicon signals with values ofchemical shifts −80 ppm, −100 ppm, −115 ppm, and the ratio of theirintegral intensities close (but not necessarily) to 2:2:1 of the generalempirical formula, ({CH₃SiO(OH)}x·(CH₃SiO_(1.5))y·(2H₂O)z)_(n),

where x—from 0.1 to 0.9; y—from 0.9 to 0.1; z—from 1.55 to 2.55, n—morethan 2

The proposed method provides the process of spatial non-linear growth ofthe polymeric chain and contributes to formation of a globular structurethat ensures formation of pores, and, accordingly, provides adsorptionactivity to the sorbent in the declared method.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a graph illustration of infrared spectra confirming thebranched organosilicone polymerous polynuclear compound of theinvention.

FIG. 2 shows a graph illustration of analysis by the Si²⁹NMR method.

DETAILED DESCRIPTION OF THE INVENTION

According to the claimed invention, in the beginning of the obtainingprocess of the product of the hydrolysis of methyl trichlorosilane ofthe general formula (CH₃SiO₂Na)_(n), is subjected to alkaline treatmentuntil the dissolution process is complete, water is added to achieve aconcentration of the product of the hydrolysis of methyl trichlorosilanenot less than 250 g/l, which according to the analysis by Si²⁹NMRmethod, comprises at least three superposition of silicon with values ofchemical shifts −18 ppm, −26ppm, −33 ppm. After, processing of theproduct is carried out by solution of strong acid, ensuring formation ofhydrogel, which, after completion of the polycondensation is pulverizedand treated with a dilute solution of strong acid, followed by washingwith water until the neutral reaction and obtaining the target product,which has the general empirical formula:

({CH₃SiO(OH)}x·(CH₃SiO_(1.5))y·(2H₂)z)_(n),

where x—from 0.1 to 0.9; y—from 0.9 to 0.1; z—from 1.55 to 2.55, n—morethan 2and which according to the analysis by Si²⁹NMR method containssuperpositions of at least three silicon signals with values of chemicalshifts - 80 ppm, - 100 ppm, - 115 ppm, and ratio of their integralintensities close to 2:2:1.

It is advisable, after treatment with alkaline before completion of thedissolution process, to add water in ratio 1:0.3-0.4:0.7-2, andtreatment with a strong acid solution to carry out in a volumetric ratioof components 5-10 to 1.

In addition, crushed hydrogel can preferably be treated with a dilutesolution of strong acid, having temperature not higher than 15° C. andconcentration from 0.02 to 0.2 g·equ/1.

As conducted experiments show, as a result of synthesis at giventemperature regime of the reaction mixture, the target product with thefollowing physical and chemical properties, presented in Table 1 with ahigh sorption capacity to high molecular toxins (toxic agents), isformed.

TABLE 1 Influence of synthesis temperature on the appearance of thetarget product and its output Value of temperature of the synthesisTarget Target No. of reaction of the product product experiment targetproduct output, % properties 1 35 — product has no form 2 30 — 3 25 30 ±5 amorphous mass 4 20 60 ± 5 amorphous mass 5 15 70 ± 5 Amorphous mass 610 70 ± 5 weakly gel-like mass 7 9.5 78 ± 5 Gel-likr mass 8 8 80 ± 5Stable gel-like mass 9 7 80 ± 5 stable gel-like mass 10 6 85 ± 5 stablegel-like mass 11 5.5 80 ± 5 stable gel-like mass 12 5 80 ± 5 stablegel-like mass 13 0 80 ± 5 Stable gel-like mass

Compounds, synthesized according to the claimed method, are also asecond aspect of the protection of the present invention.

Mentioned synthesized compounds have been analysed by Si²⁹NMR method,for the content of water, silicon, carbon and hydrogen.

The adsorption activity (A) of the obtained target product has beendetermined by their ability to absorb Congo red and methyl orange fromaqueous solution, as well as high molecular bacterial toxin.

Determination of the adsorption activity has been carried out accordingto methods, described in Patent RU 2293744.

Below, specific Examples of preferred embodiments of the synthesis ofthe target product with reference to the figure of drawings are given,where FIG. 1 provides experimental IR spectra of dehydrated hydrogels,obtained in accordance with the invention in the frequency range400-1400⁻¹, where valent fluctuations of groups Si—O(Si) are manifested,and FIG. 2—data of the analysis of the compound, obtained according tothe claimed technique by Si²⁹NMR method.

Example 1

100 liters of water were poured into the reactor and 12 liters ofmethyltrichlorosilane (MTCS) were added (about 15.24 kg) during stirringfor 1 hour. The mixture was stirred for 30 minutes with the aid of astirrer and then hydrochloric acid was separated by filtration during 15min. After that, the cycle was repeated. In this process, the reactionmixture was heated to temperature of 60-70° C. The washing of theproduct, formed as a result of two cycles, was carried out in the samemode until the acidity of washing waters was equal to pH 5.0. 12.4 kg ofthe product of the hydrolysis of MTCS was obtained (output of about 80%by weight)

The resulting product of the hydrolysis of trichloromethylsilane wassubjected to treatment with alkaline—sodium hydroxide—not less than 97%in such a ratio of components' masses: for 1 fractional of the productof the hydrolysis not less than 10 weight fractions of sodium hydroxideuntil completion of the dissolution process, followed by addition ofwater to achieve concentration of the product of the hydrolysis ofmethyltrichlorosilane not less than 250 g/l.

31 kg of hydrated product of the hydrolysis of MTCS, containingaccording to data of Si²⁹NMR at least 3 types of silicon atoms andcharacterized by the presence of a superposition of three siliconsignals with values of chemical shifts −18 ppm, −26 ppm, −33 ppm, andratio of their integral intensities close to 2:2:1 is obtained.

After that, the resulting product was added with a solution of sulfuricacid (not less than 30%) of 3.4 liters. After 1.3 minutes, gel product(sedimentation) was obtained. After pulverizing and washing from acid toneutral washings, 37.2 kg of hydrogel polymeric organosiliconepolynuclear adsorbent was obtained, which according to the analysis bySi²⁹NMR method, comprises superposition of at least three siliconsignals with values of chemical shifts −80 ppm, −100 ppm, −115 ppm, andratio of their integral intensities close to 2:2:1.

The resulting product had a gelled/gel form of almost white colour; notsoluble in water and organic solvents; had pH equal to 6.0; dry residuewas 8.88%; silicon content was 3.94%; along with that adsorptionactivity was 3.0 μmol/g.

Example 2

200 liters of water were poured into the reactor and 25 liters of methyltrichlorosilane (MTCS) (about 31 kg) were added during stirring for 1hour. The mixture was stirred for 50 minutes with the aid of a stirrerand then hydrochloric acid was separated by filtration for 30 min. Afterthat, the cycle was repeated. In this process, the reaction mixture washeated to temperature of 60-70° C. The washing of the product, formed asa result of two cycles, was carried out in the same mode until theacidity of rinsing waters was equal to pH 5.5. 22 kg of the product ofthe hydrolysis of MTCS was obtained (output of about 70% by weight)

The resulting product of the hydrolysis of trichloromethylsilane wassubjected to treatment with alkaline—sodium hydroxide—not less than 97%in such a ratio of components' masses: for 1 fractional of the productof the hydrolysis not less than 10 weight fractions of sodium hydroxideuntil completion of the dissolution process, followed by addition ofwater to achieve concentration of the product of the hydrolysis ofmethyl trichlorosilane not less than 250 g/l.

60 kg of hydrated product of the hydrolysis of MTCS, containingaccording to data of NMR Si²⁹ at least 3 types of silicon atoms andcharacterized by the presence of a superposition of three siliconsignals with values of chemical shifts −18 ppm, −26 ppm, −33 ppm, andratio of their integral intensities close to 2:2:1 is obtained.

After that, the resulting product was added with a solution of sulfuricacid (not less than 30%) of 5 liters. After 1.5 minutes, gel product(sedimentation) was obtained. After pulverizing and washing from acid toneutral washings, 72.2 kg of hydrogel was obtained from polymerousorganosilicone polynuclear adsorbent, which according to the analysis bySi²⁹NMR method, comprises superposition of at least three siliconsignals with values of chemical shifts −80 ppm, −100 ppm, −115 ppm, andratio of their integral intensities close to 2:2:1.

The resulting product had a softgell form of almost white colour; notsoluble in water and organic solvents; had pH equal to 6.3; dry residuewas 8.9%; silicon content was 3.90%; along with that adsorption activitywas 2.8 μmol/g .

Thus, the indicated method allows to obtain an end- product, of astabile composition, and which according to the analysis by Si²⁹NMRmethod contains superpositions of at least three silicon signals withvalues of chemical shifts −80 ppm, −100 ppm, −115 ppm, and ratio oftheir integral intensities close to 2:2:1.

The chemical structure of the obtained branched organosiliconepolymerous polynuclear compound is confirmed by infrared spectra,obtained in the frequency range from 400 to 1400 cm⁻¹, given in FIG. 1,which show valent fluctuations of groups Si—O(Si), by Si²⁹NMR method,which made it possible to distinguish between changes in the nature ofthe environment of resonant silicon atoms, a qualitative reaction tosilicon, the method of elemental analysis, which indicates ratio ofelements in the structure.

To show experimentally the structure of the globular matrix of theproduct, pore solvent water was removed by heating at 130° C. andrecorded by IR. IR spectra in range 400-1400⁻¹ were recorded by Shimadzuspectrophotometer.

The resulting product had a slightly gel/gelled form of almost whitecolour; not soluble in water and organic solvents; had pH equal to 6.3;dry residue was 8.9%; silicon content was 3.90%; herewith adsorptionactivity was 2.8 μmol/g.

As can be seen from FIG. 1, the experimental spectrum records threeintensive absorption bands at 1003 cm⁻¹, 1132 cm⁻¹ and 1274 cm⁻¹.Frequencies in range 2800-3750 cm⁻¹ relate to valent fluctuations ofSi—OH groups. The presence in the spectrum of hydroxyl groups indicatedthe possibility of formation along with chemical bonds, intraglobularbonds. It is known that absorption bands of Si—O bonds are in the range900-1000 cm⁻¹, in three-dimensional absorption structures Si—O-bonds areobserved in range 1050-1200 cm⁻¹.

According to the data obtained from the analysis by Si²⁹NMR method,shown in FIG. 2, the investigated compound contains at least three typesof silicon atoms, characterized by the presence of superposition ofthree silicon signals (d and e—synthesized compound, f—xerogel ofsynthesized compound, and b—model kuban—polymer, which contains aSi—O—Si dimer as a monomer component and is characterized by a singlesilicon signal) with values of chemical shifts −80 ppm, −100 ppm, −115ppm, and ratio of their integral intensities close to 2:2:1.

Thus, it is confirmed that there is a dependency between the presence ofthree types of silicon atoms in the basic substance for synthesis of thefinal product, which indicates polynucleosis and branching, and allowsthe polymerization reaction to be carried out precisely at the expenseof these groups and the structure of the final product (more negativevalues the chemical shift in comparison with the basic product (theproduct of the hydrolysis of methyl trichlorosilane) indicatepolymerisation). Changes in the concentration parameters of thereaction, starting with the hydrolysis of MTCS, and ending with gel,will lead to a change in the structure of the finished product.

Studies of infrared spectra of the obtained compounds have been carriedout. Frequencies in range 2800-3750cm⁻¹ of infrared spectra relate tovalent fluctuations of Si—OH groups and indicate the possibility offormation of intraglobular bonds along with the chemical bonds, thatconfirms the branched globular structure of the claimed compound.

More over, the globular structure is confirmed by studies in terms ofdetermination of the pore size and specific surface area, and theadsorption activity of benzol, which are shown in Table 2.

TABLE 2 Capacity for benzol, g/cm³ Sample No. 1: synthesizedorganosilicone 0.73 Sample No. 2 synthesized organosilicone 0.83activated charcoal (control, GOST) 0.46

The chemical structure of the claimed substance is also proved, usingthe elemental analysis by method of laser analysis of the elementalcomposition with the use of LEA-S500 apparatus, the results of which aregiven in Table 3.

As follows from Table 3, the proportion of silicon, carbon and hydrogenin the adsorbent according to the invention coincides with thecalculated values of these figures. Thus, using the elemental analysis,the chemical structure of the declared adsorbent has been confirmed.

TABLE 3 Elemental composition of organosilicone sample Element C Si HFound, % 20.0 40.5 5.0 Calculated, % 18.0 41.8 4.5

Thus, ratio of elements: C 0.49: Si 1: H 0.12 corresponds to thedeclared empirical formula.

To confirm affinity of high molecular toxicagens, measurement of theadsorption activity for high molecular substances—immunoglobulin G (morethan 100,000 Da) and bacterial toxin (more than 10,000 Da) wasperformed.

The results are shown in Table 4.

TABLE 4 Comparative experimental data on the study of properties of theprototype and the claimed technical solution Name of indicatorsPrototype Claimed technical No. compared indicator solution indicator 1Methylene blue 3.2 μmol/g 3.2 μmol/g 2 Immunoglobulin G 182.2 μmol/g336.4 μmol/g 3 Bacterial toxin 6.22 μmol/g 9.13 μmol/g

As follows from the results of Table 4, the branched polymerouspolynuclear adsorbent exhibits more signified activity in relation tohigh molecular compounds and exceeds such activity for the prototype in1.5-1.83 times.

1. A method for obtaining of a branched polymerous polynuclear adsorbentof high molecular toxins, according to which the product of thehydrolysis of methyl trichlorosilane of a general formula(CH₃SiO₂Na)_(n), is subjected to alkaline treatment until completion ofthe dissolution process, water is added to achieve a concentration ofthe product of the hydrolysis of methyl trichlorosilane not less than250 g/l, which according to the analysis by Si²⁹NMR method, comprises atleast three superposition of silicon with values of chemical shifts 18ppm, 26 ppm, 33 ppm, the product is processed with a solution of strongacid, ensuring formation of hydrogel, which, after completion of thepolycondensation process is pulverized and treated with a dilutesolution of strong acid, followed by washing with water until theneutral reaction and obtaining of the target product, which has thegeneral empirical formula:({CH₃SiO(OH)}x·(CH₃SiO_(1.5))y·(2H₂O)z)_(n), where x—from 0.1 to 0.9;y—from 0.9 to 0.1; z—from 1.55 to 2.55, n—more than 2 and whichaccording to the analysis by Si²⁹NMR method contains superpositions ofat least three silicon signals with values of chemical shifts −80 ppm,−100 ppm, −115 ppm, and ratio of their integral intensities close to2:2:1.
 2. The method of claim 1, by which after treatment with alkalinetill completion of the dissolution process, water is added in ratio1:0.3-0.4:0.7-2.
 3. The method of claim 1, by which treatment withstrong acid solution is carried out in a bulk ratio of components 5-10to
 1. 4. The method of claim 1, by which pulverized hydrogel is treatedwith a dilute solution of strong acid, having temperature not higherthan 15° C. and concentration from 0.04 to 0.15 g·equ/1.
 5. Acomposition of branched polymerous polynuclear adsorbent of highmolecular compounds of the general empirical formula,({CH₃SiO(OH)}x·(CH₃SiO_(1.5))y·(2H₂O)z)_(n), where x—from 0.1 to 0.9;y—from 0.9 to 0.1; z—from 1.55 to 2.55, n—more than 2 which is obtainedby the method according to paragraphs 1-4 and which according to theanalysis by Si²⁹NMR method contains superpositions of at least threesilicon signals with values of chemical shifts −80 ppm, −100 ppm, −115ppm, and the ratio of their integral intensities close to 2:2:1.